Heat Stability of Lipases of Selected Psychrophilic Bacteria in Milk and Purdue Swiss-Type Cheese

Pinheiro, A.J.R.; Liska, B. J.; Parmelee, C. E.

doi:10.3168/jds.s0022-0302(65)88372-2

Cited by 22 publications

(12 citation statements)

References 5 publications

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“…Nashif and Nelson (9) reported that cream and butter made from milk contaminated with Pseudomonas fragi had a pronounced off-flavor. A similar observation made by Pinheiro et al (10) was that the lipolytic enzymes produced by P. fragi and P. mucidolens were thermostable, and the residual lipases after heat treatment of the milk caused undesirable flavors in Swiss-type cheese. In 1953, Nashif and Nelson (7, 8) made a systematic study of the properties of the lipase ofP.…”

supporting

confidence: 74%

Lipase from Pseudomonas fragi. I. Purification of the Enzyme1

Lu¹,

Liska²

1969

Applied Microbiology

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The experimental conditions required to isolate a lipase from Pseudomonas fragi were determined. The organism was grown in a buffered tryptone medium for 4 to 5 days at 20 C. The lipase in the culture supernatant fluid was isolated by fractionation with ammonium sulfate at 60% saturation, followed by acetone precipitation at 30-60% concentration. Further purification was made by using Sephadex G-200 gel-filtration and diethylaminoethyl cellulose chromatography. Electrophoretic analysis of the purified lipolytic fraction showed apparent homogeneity by both cellulose polyacetate and disc electrophoresis. The specific activity of the purified enzyme was about 100 times that of the starting culture filtrate, and the yield was about 1.8% of the original activity. Some bacteria and fungi are capable of causing undesirable changes in foods stored at temperatures of 0 to 10 C. A flavor problem encountered

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supporting

confidence: 74%

Lipase from Pseudomonas fragi. I. Purification of the Enzyme1

Lu¹,

Liska²

1969

Applied Microbiology

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“…When the raw milk was of inferior bacteriological quality, it was often found that the cheese made from the milk after heat-treatment, developed flavour and texture defects, due mainly to the deleterious action of the lipases and proteases produced by actively multiplying strains of psychrotrophic pseudomonads during the cold storage of the milk, (Pinheiro, Liska & Parmelee, 1965;Vassal & Auclair, 1966;Ritter, 1970;Bottazzi, 1970;Vassal & Mocquot, 1970). When the raw milk was of inferior bacteriological quality, it was often found that the cheese made from the milk after heat-treatment, developed flavour and texture defects, due mainly to the deleterious action of the lipases and proteases produced by actively multiplying strains of psychrotrophic pseudomonads during the cold storage of the milk, (Pinheiro, Liska & Parmelee, 1965;Vassal & Auclair, 1966;Ritter, 1970;Bottazzi, 1970;Vassal & Mocquot, 1970).…”

Section: (C) Cheesemakingmentioning

confidence: 99%

“…Several other workers have shown that good quality cheese can only be achieved when the bacteriological quality of the bulk collected milk is mtisfactory. When the raw milk was of inferior bacteriological quality, it was often found that the cheese made from the milk after heat-treatment, developed flavour and texture defects, due mainly to the deleterious action of the lipases and proteases produced by actively multiplying strains of psychrotrophic pseudomonads during the cold storage of the milk, (Pinheiro, Liska & Parmelee, 1965;Vassal & Auclair, 1966;Ritter, 1970;Bottazzi, 1970;Vassal & Mocquot, 1970).…”

Section: (C) Cheesemakingmentioning

confidence: 99%

Influence of Production Conditions on the Bacteriological Quality of Refrigerated Farm Bulk Tank Milk—A Review

Thomas

Druce

Jones

1971

Journal of Applied Bacteriology

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“…The samples assayed contained 1 mg of ATF protein per ml. DISCUSSION P. fluorescens is a saprophytic bacterium (27) occurring in soil and commonly found as a contaminant of water, milk, and other refrigerated dairy foods (16)(17)(18)23). It is psychrophilic and grows best at room temperature.…”

Section: Resultsmentioning

confidence: 99%

“…For example, lysis of Staphylococcus aureus was produced by both P. aeruginosa and P. fluorescens (28). A protease was characterized from strain 26 of P. fluorescens, and lipase activity was exhibited by both P. fluorescens and P. fragi (16)(17)(18)22). However, these substances appear to be different from those reported in this study, e.g., in regard to molecular weight and resistance to heat and freezing.…”

Section: Resultsmentioning

confidence: 99%

Lysis of Trypanosoma cruzi by Pseudomonas fluorescens

Mercado

Colón-Whitt

1982

Antimicrob Agents Chemother

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Trypomastigotes of Trypanosoma cruzi isolated from the blood of infected mice were lysed within 24 h by an extracellular substance produced by Pseudomonas fluorescens. Isolation of the anti-trypanosomal factor (ATF) was accomplished by growth of the organisms in a defined medium, extracellular secretion by the sedimented cells, sterilization by filtration, lyophilization, dialysis, and gel filtration. Chromatographic separation with Sephadex G-25 and G-200 disclosed the occurrence of three active fractions. ATF-I(1) exhibited a molecular weight higher than 440,000. ATF-II and ATF-III were considerably smaller (molecular weights approximately 1,355 and 1,060, respectively). The lytic substance contained protein and lipopolysaccharide, was resistant to heat and freezing, was not proteolytic or hemolytic, and was not inhibited by trypsin but was suppressed by pronase.During studies of Trypanosoma cruzi, we observed that the number of trypomastigotes isolated from the blood of infected mice markedly diminished when maintained in vitro at 4°C for 3 days. Microscopic examination revealed that the parasite samples had become contaminated by a small, motile, rod-shaped microorganism that was attracted to the parasites, particularly to the posterior end. As a result of the interaction, the trypomastigotes became immobilized, and most were lysed within 24 h. A gram-negative bacterium isolated in blood agar and nutrient broth cultures was identified as Pseudomonas fluorescens by the Clinical Pathology Department, National Institutes of Health. We considered these observations to be significant not only in terms of cellular biology and physiology, but also because of their potential significance in the chemotherapy of Chagas' disease; further studies were therefore conducted to analyze the parasite-bacterium interaction.MATERIALS AND METHODS Parasites. The Tulahuen strain of T. cruzi is routinely maintained in this laboratory by blood passaging every 6 days in NIH-Swiss 16-to 20-g male mice; 4 x 106 to 5 x 106 trypomastigotes are usually inoculated intraperitoneally (14). The infection becomes acute after 6 days, producing marked pathology of liver and spleen, and blood counts of 108 parasites per ml are often obtained. The animals are not immunosuppressed. Blood samples are obtained under ether anesthesia directly from the heart after exposure of the cardiac surface. Parasites were isolated from blood by a two-step procedure (15) involving separation of the erythrocytes with Lymphoprep (9.6% sodium-Nmethyl-3,5-diacetamido-2,4,6-triiodobenzoate and 5.5% Ficoll; specific gravity, 1.077; Nyegaard and Co., Oslo, Norway) and elution through a DEAEcellulose column to remove lymphocytes and platelets. The eluted flagellates exhibited the usual lanceolate shape (6), were actively motile and elicited typical infections. Two myotropic strains of T. cruzi, the House 510 and the House 11, of Costa Rican and Nicaraguan origin, respectively, trypomastigotes of T. rhodesiense 1886, T. equiperdum, and promastigotes of Leishmania brasilien...

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Heat Stability of Lipases of Selected Psychrophilic Bacteria in Milk and Purdue Swiss-Type Cheese

Cited by 22 publications

References 5 publications

Lipase from Pseudomonas fragi. I. Purification of the Enzyme1

Lipase from Pseudomonas fragi. I. Purification of the Enzyme1

Influence of Production Conditions on the Bacteriological Quality of Refrigerated Farm Bulk Tank Milk—A Review

Lysis of Trypanosoma cruzi by Pseudomonas fluorescens

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